Centralized traffic controlling and communicating system for railroads



Oct. 21, 1941. w, 3, HMLES ETAL 2,259,562

CENTRALIZED TRAFFIC CONTROLLING AND COMMUNICATING SYSTEM FOR RAILROADS Filed May 8, 1940 7 Sheets-Sheet l FILO I INVENTORS VglaHai les and EWBrixner' THEIR ATTORMEY 1941- w. 13. HAILES EIAL CENTRALIZED TRAFFIC CONTROLLING AND COMMUNICATING SYSTEM FOR RAIL ROADS Filed May 8, 1940 7 Sheets-Sheet 2 J e I n x n U 2 sn m n o d N "m m a M H.EH m Q a N T. H E 5% m Mm m ai i 3 8 SQ a 2 0 QM v 3 8m i AQW FOG a $Y 3 EYY E M u mdmlr Oct. 21, 1941.

W. D. HAILES ETAL CENTRALIZED TRAFFIC CONTROLLING AND COMMUNICATING SYSTEM FOR RAILROADS '7 Sheets-Sheet 3 Filed May 8, 1940 0 2m m 6 2, m H" 0 la a: v m MM NU W a Y m a Oct. 21, 1941. w.' D. HAILES mu. CENTRALIZED TRAFFIC CONTROLLING AND GOMMUNICATING SYSTEM FOR RAILROADS Filed May 8, 1940 7 Sheets-Sheet 4 I INVENTORS WDHailes and 'EWBrixner wMm-w THEIR ATTORNEY TV EFQU Rm W. D. HAILES ETAL Oct. 21, 1941.

CENTRALIZED TRAFFIC CONTROLLING AND COMMUNICATING SYSTEM FOR RAILROADS 7 Sheets-Sheet 5 Filed May 8, 1940 INVENTORS W.D.Ha.iles and FWBrixner THIMTOMNEY C 21, 1941. HAILES Em 2,259,562

CENTRALIZ ED TRAFFIC CONTROLLING AND COMMUNICATING SYSTEM FOR RAILROADS Filed May a, 1940 7 Sheets- Sheet 6 F G C; Field Station No.1.

MW ca d? 12 16 C14 v INVENTORS WDHa'ules and EWBrixner l BY . 411 106 151 11 1 ISA' l 05 I 132 411 22'?" 1= --.l k l W 5 I T 05 W w I 1a 1 0a. 21, 1941. D, HAIL S Em 2,259,562

R RAILROADS GENTRALIZED TRAFFIC CONTROLLING AND COMMUNICATING SYSTEM F0 7 Sheet s-Sheet 7 Filed May 8, 1940 1ao F: 4.

INVENTORS ai les :2.

M 1 a w 2 4 F I a w. ll ifl m W.D.H n EWBrixner- BY Mm 266 a? THEMORN EY Patented Oct. 21, 1941 CENTRALIZED AND COMlVIUNICATING RAILROADS William D. Hailes, Brighton,

Brixuer, Gates, N. Y., assignors to TRAFFIC CONTROLLING SYSTEM FOR and Frederick W. General Railway Signal Company, Rochester, N. Y. Application May 8, 1940, Serial No. 334,022

31 Claims.

The present invention relates to a centralized traffic controlling system of the coded type upon which is superimposed a telephone system with selective ringing of the coded type.

In the application of centralized trafiic control to a railway system through the medium of which switches and signals may be controlled at many distant points along the railway through the medium of codes transmitted over a single line circuit it is often found that communication by telephone is necessary over the same territory, and inaccordance with the present invention it is proposed to carry out centralized trafiic control and telephone communication over the same pair of line Wires. In one particular type of centralized 'traffic control of the coded type distinctive controlcodes are transmitted from a central ofiice to any one of a large number of field stations by the transmission of a large number of impulses for each code, which impulses are arranged in a code pattern wherein the code characters reside in the distinctive polarity of these impulses and wherein indications are transmitted from any one of these field stations to the central oilice through the medium of codes each comprising a large number of impulses in which these impulses are distinctive by being either long or short or by having the time spaces between these impulses distinctive by being either long or short. One form of such centralized traffic control system is disclosed in applicants prior application Ser. No. 197,404 filed March22, 1938, now Patent No. 2,259,561 granted Oct. 21, 1941.

In this particular prior application a first series of impulses in each control code cycle is employed to select a particular field station by picking up a station selecting relay and in a second series of such impulses particular trafiic controlling devices at such field station are controlled and during the last impulse of such series the station selecting relay at the station selected is again deenergized, so that the station selecting relay as therein used cannot be used after the control code for the field station has been completed. Also, in thisparticular type of centralized traffic controlling system there are provided cycle marking relays which are slow dropping and which will re-' main up during intermittent deenergization of the line circuit but which will be released during a long period of deenergization of the line circuit. Furthermore, this particular type of centralized trafilc controlling system includesapparatus in the ofilce whereby when the desired number of control impulses have been transmitted to the r field-station the control-ofiice leaves the line circuit deenergized thereby dropping the cycle marking relays at the control oflice and at each one of the field stations after which the line circuitis again energized.

In accordance with the present invention it is proposed tomodify this particular type of centralized traffic controlling system of said Patent No. 2,259,561 by'employing a special circuit in the control oflice for holding the negative pulsing relay NC energized when .thelaststepping relay LV inthe control oifice is energized only under those conditions when it is desired to transmit a telephone code over the line circuit after the particular field station at which-this'telephone code is to be employed has been selected (seebranch circuit in heavy lines includingtront-contact 421 of relay LV and front contact 581 of relay CDTI Figs. 1A and IA). It is further proposed in accordance with this invention toemploy asecondary or telephone station selecting relayat such field station at whicha telephone code is to be received, this secondary station-selecting relay being energized in response to the-energization of the last stepping relay LV at such field'station, this supplemental or telephone station selecting relay remaining energized so long as the linecircuit remains'either intermittently or continuously energized (secrelay ISOT Figs. ;1B and 7D). It is further proposed in-accordance With-thepresent invention to employ a supplemental code determining relay in the control office for the panel for each way station to which a telephone code is to be transmitted, this supplemental code determining relay CDT being interlocked with all of the other code determining relays 'CD so that only one code determining relay canbe'energizedat any one time, this code determining relay being employed to render the coding key, such as key KIA (Figs. 1A, 2 and 7A) efiective to transmit a telephone calling codeat the end of the station selecting and control code, providing that the operator in the control office in response to the sounding of a buzzer has operated a coding key, such as KIA (see relay CDTI) Another object of the present invention residesin the-provision of such a buzzer which is sounded when a particular station has been selected by the centralized'trafiic controlling code system for the-purpose ,of transmitting a telephone code to such system, together with means for silencing suchbuzzer whenthe operator has operated and released atelephone coding key for transmitting a telephone code to theselected fieldstationv (see buzzer BUZ).

Another object of the present invention resides in the provision of suitable filtering apparatus which enables a telephone communication to be carried on over the wires of the centralized traific controlling system during the transmission of a centralized traffic control code or indication code or the transmission of a telephone calling code without interfering with the audibility of the telephone communication, this filtering apparatus being constructed to perform its functions irrespective of whether the centralized traflic transmitting code is a control code or anindication code and irrespective of whether a particular lock-out relay L is then energized and irrespective of whether the line is then being coded by a coding relay, such as relay E at .the field the same or some other field station, this result being accomplished irrespective of whether the telephone cornmunication'is carried on betweenthe ofiice and the telephone located beyond the transmitting field station or whether the transmitting fieldv station is beyond the station'at which the telephone then in-use is branched off.

Other objects, purposes and characteristic fea tures of this invention will in part be pointed out in the specification hereinafter and will in part be obvious from the accompanying drawings, in wh ch ,Fig.-.1A discloses rather conventionally the ofiice apparatus of the composite centralized traffi c control code and telephone code system;

Fig. 1B illustrates the line circuit of such systern together with two field station equipments;

,Fig. 2 shows a telephone coding key an element .of the present invention;

Fig. .3 shows the telephone selector SIA of the telephone system superimposed on the centralized traflic controlling system;

Figs. l, 5 and 6 show the telephone selector of 3 energized negatively, positively and deenergized respectively.

'Figs, 'ZA and 7b illustrate the ofilce apparatus disclosed in ourprior application above referred to except that the push button B2, the change relay CH2, and the code determining relay CD2 have beenomitted therefrom, and that additional apparatus embodying the improvements of the present invention over that of the invention in said patent has been superimposed thereon. All of the relays, devices and circuits of said prior application being shown in light lines, whereas the superimposed apparatus and circuits have been shown in heavylines'; Figs. 7C and 7D illustrate a field station apparatus of our said prior application in light lines having superimposed thereon in heavy lines the necessary. wiring and apparatus for selectively ringing a telephonestation and for carrying on a telephone communication over said system during the transmission of a trafiic controlling, trafiic indication or a telephone calling code; and

Fig. 8 illustrates a modified construction of that part of the line circuit located in the control office.

' C. T. C.,o17ice apparatus Since the office equipment of the centralized trafiic controlling system has been described in detail in our above mentioned patent this apparatus will only be briefly described herein. In order to distinguish the wiring and apparatus disclosed in our said patent from the apparatus that has been added to disclose the combination embodying our present invention the apparatus of such' p'atent is shown by light lines,

whereas the added apparatus and circuits are shown by heavy lines.

Referring to Figs. 7A and '73, when laid one above another with the stepping relays in registration, disclose by the light lines contained therein the ofiice equipment shown in Figs. 2 and 3 of our said patent. This apparatus includes line wires I0 and I8 extending from the ofiice to the field stations (see also Figs. 70 and 7D). These line wires may be energized by current of positive polarity when the pulsing relay PC is energized and may be energized by current of negative polarity when the pulsing relay NC is energized, and will be so energized if either the relay CO (designated relay C in said patent) or the relay CF is energized or if the relay OR is deenergized. These pulsing relays PC and NC may be energized in many different ways as indicated by the circuits shown in Fig. 7A, but for the purpose of transmitting a particular code for selecting the first field station consists of a pattern of positive and negative current impulses selected over code jumpers Bl, I6 and 12, and'are controlled over similar code jumpers arranged to modify the order of these impulses when some other field station is to be selected.

This ofilce equipment also includes cycle marking and repeater relays SA, SB, SC, SD and 0C all controlled in a manner as described in detail in our said patent above identified. The ofiice equipment also includes a line relay F and a line repeater relay FA. The stepping relays VI, V2, V3, V4 and the last stepping relay LV' are controlled in a well known manner and as disclosed in our said patent through the medium of a contact 92 of the half-step relay VP, the'back contact 9| of the line repeater relay FA and the front contact of the cycle marking repeater relay SC. These stepping relays V determine by their contacts 6|, 62, 63 and 64 each in combination with its particular jumper such as 61, ID or 72, whether such contact shall be effective to control the pulsing relays PC or NO, these jumpers however being ineifective unless their associated code determining relay, such as relay CDI, is energized. In order to energize one of these code determining relays, such as CDI, a change relay, such as relay CHI, has been provided. Each of these change relays may be picked up, as by a push button BI, and if once picked up is stuck up as through the medium of back contact of its associated code determining relay, such for instance, as back contact 40 of the code determining relay CDI for the change relay CHI.

Briefly stated the ofiice apparatus of the CTC system may apply to the line circuit a code made up of an assortment of positive and negative impulses in a manner as presently described. For instance, if the operator depressed the push button B he will pick up the change relay CHI which will then stick up through the back contact 40 of the code determining relay CDI. With the change relay CHI up its closed front contact 45 will close an energizing circuit for the code determining relay CDI, which includes back contact M of relay SC, back contact 42 of relay CF, back contact 43 of relay CDS, back contact 5'II of relay CHTI, front contact 45 of change relay CHI and the normally closed push button contact 39 of the cancelling push button CNB. As soon as the code determining relay CDI has been picked up the closure of its front stick contact 41 closes a stick circuit including the lower winding of this code determining relay 4.6, 48 and 49 of the relays LV,

CD'S closes an energizing circuit for the relay CO which includes back contact 50 of relay SC,

front contact fat of relay ODS, and back contact 52 of relay CF. Picking up of this ofiice start relay CO (designated C in our said prior application) causes closure of its front contact 16 in the line circuit Ill-43 thereby shunting the stick contact ZI of the line relay F, so that this line relay F becomes a non-stick relay instead of a stick relay as is the case when the apparatus is in its normal non-signalling condition. The office apparatus is now in condition to apply a series of impulses to the line circuit III-=48, these impulses characterizing a code as determined by the jumpers rendered effective by energization of the code determining relay CDI,- and this code is of a character to render efiecti've the apparatus at the field station No. 1 shown in Figs. l'B, 7C and 713. For a'more complete description of the C. T. C. apparatus shown in Figs. 'IA and 7B reference should be had to our patent above referred to.

In' addition to the apparatus above mentioned the ofnce is provided with a miniature track layout including a miniature track switch is, a switch machine control lever SMLI, decoding relays TON, TOF, LON and LOF and a pulsing repeatm relay EP.

I I I C. T. C. field station apparatus Referring now to Figs. 7C and 7D of the drawings, these drawings when laid side by side illustrate the apparatus located at an intermediate field station of the present invention and the relays, devices and circuits which are shown in light lines show the apparatus disclosed in Figs. 5A and 5B of our said patent.

Referring to Figs. 7C and 7D attention is directed to the fact that the line relay IF is of slightly modified construction from that of the line relay shown in our said patent, in'that a double winding relay has been illustrated of which one winding is included in series with one of the two line wires and the other winding is included in series with the other line wire of" the 'C. T. C. system; Attention is also directed to the fact that the lock-out relay ILO and the line pulsing relay IE create double makes and double'breaks in the line wires of the system in the present application as distinguished from single makes and single breaks in the said patent. The double winding for the relay IF and the double contacts for the relays ILO and IE have been resorted to in order to result in an equal potential and impedance gradient along each line wire of the two line wires It and I8 irrespective of induction from other circuits, other foreign sources or the sudden making and breaking of the circuit by various relays. For instance, the impedance of the two windings of the relay IF are substantially identical so that even though there is a sudden change in current due to an external influence, such as lightning or a sudden change of current in an adjacent circuit, there will be substantially no potential difference across the lines it! and I8 due to the induced current. Similarly, opening of the line circuit by one of the relays, such as relay ILO or IE, will cause a break to occur in both wires at the same time, thus maintaining the impedance of each line wire in approximate balance with that of the other line wire and thereby limiting to a negligible value the potential diiference which may appear across lines Ii! and I8due to currents induced in these lines by external sources just prior to such break.

The field station apparatus insofar as the centralized traffic control features thereof are concerned includes a station selecting relay ISO and'an associated relay ISO'S. These relays are picked up at the beginning of a control cycle ina manner as fully described in our said patent and these relays will remain energized only so long as the successive polarity code impulses transmitted to such field station from the office are in an order in conformity with the code assigned to that field station. For instance, suitable code jumpers, such as code jumpers I453, MI and I42, are provided at each field station, these code jumpers are connected to enable current to flow from the polar contact 36 of the line relay IF to these relays ISO and ISOS only if the polar position of this contact 33 conforms to the positions assigned to the jumper I49, Hit or I42. For instance, since the code jumper I42 is positioned in its lowermost position the contact 30 of the relay IF must be in its left-hand position when the stepping relay V3 is energized. Similarly, this contact 38 must be in its righthand position when the stepping relays IV or 2V is energized, this by reason of the fact that the jumpers I45! and I l! are in their upper position. In other words, the relays ISO and i803 will receive pulses of current from the contact 38 of the line relay IF only if the code pattern applied to the line circuit at the control ofiice conforms to the code pattern as determined by jumpers Hill, This relay ISO is maintained energized between impulses through the medium of the back contact I38 of the line repeater relay IFA, but relay ISOS drops during an off period after relay IFA drops. Also, the relay ISO is maintained energized by another stick circuit through the front contact I52 of the stepping relay V4 during the time that the stepping relay V4 is up, namely, the time when a particular trafnc controlling device at such field station, such as the relay SMR, is controlled. When, however, the code has proceeded to the last impulse, namely, the impulse period when the last stepping relay LV is energized the back contact I44 of this relay LV is opened so that the front contact I52 of the stepping relay V4 can no longer hold the relay ISO energized, so that the station selecting relay ISO will be deenergized and dropped during the next impulse period following the picking up of the last stepping relay LV. In order to maintain energy on this polar contact 39 of the relay IF in the system of the present invention, which formerly was derived only through front contacts I25. of the relay ISO or the back contact 29 of the relay ISB, a new contact Frill has been added to the last stepping relay LV in multiple with these contacts I25 and 29. The purpose of this additional contact 5M will be described in connection with the field station telephone apparatus.

The C. T. C. field station apparatus also includes cycle marking relays ISA, ISB, IS and IOC. These relays are energized at the beginning of a control cycle or indication cycle and are maintained energized throughout such control or indication cycle, except that the relay IOC is not deenergized between cycles if these cycles are in close succession. The various control cir- MI and H52 in the field station.-

cuits for these relays have been described in detail in our said patent to which attention is directed and for this reason will 'not be further described herein. It may, however, be pointed out that these relays ISA, I SB, IS and IOC are so controlled that they will remain energized after the completion of a control cycle which has been transmitted for the purpose of establishing telephone communication so long as the line circuit is either intermittently or continuously energized in a manner as pointed out hereinafter. It may be stated at this point that if the field apparatus shown in Figs. 7C and 7D is selected for the purpose of ringing a telephone bell, either at this station or on a branch line extending from this station, the usual station selecting code call will be transmitted to result in the energization of the station selecting relays ISO and ISOS, so that these relays ISO and ISOS will remain energized to allow the stepping of the tepping relays VI, V2, V3 and V4 to continue until a pick-up circuit for the last stepping relay LV has been completed. After this point in the code cycle has been reached the station selecting relays ISO and ISOS will be deenergized, as a result of which the last stepping relay LV is energized at only one of the field stations, namely, the field station which had its station selecting relay energized throughout the entire station selecting code cycle exclusive of the last impulse which energized the relay LV at such station. It may also be pointed out that this additional impulse when a telephone bell'isto be selected by a telephone selector at that particular field station is created in the control office through a circuit including a front contact 421 of the relay LV at the control oflice. This impulse will remain on the line and will hold all of the cycle marking relays energized until the operator in the control ofiice has in response to sounding of a buzzer in the oflice operated a telephone key belonging to that field station which in turn results in the transmission of a telephone selector code for selecting a particular telephone bell associated with the selected field station.

In addition to the equipment at the field station already mentioned the field station equipment also includes a track layout including a track switch TS operated by a switch machine SM, protected by a detector track circuit including a relay T and having associated therewith signals which if all at stop will hold the signalsat-stop relay M energized. To manifest a change in the conditions of the track switch or in the relays T or M a change relay I CH and a change repeater relay ICHP have been provided. The field station equipment also includes a half-step relay IVP, coding relays ILO-N and ILOF and a stick relay combination including relays IL and IRL. The relay IL is a series relay and is included in the stick circuit of the relay IRL and is provided with a back contact 35 included in the pick-up circuit of the relay IRL. Since, however, the pick-up circuit for the relay IRL is normally closed through contact 30 of line relay IF in its left-hand position the relay IL is normally shunted and momentary deenergization of the line circuit III-I8 and line relay IF will result in the picking up of the series relay IL and the relays IL and IRL will then both remain energized in series until a code cycle is under way to an extent to pick up the cycle marking relay ISB having a back contact 36 in the stick circuit including relays IL and IRL in series, at

which time both of these relays IL and IRL will drop. This stick feature is primarily employed to prevent picking up of a change repeater relay, such as ICHP, at any station after the L relays, such as IL, have been picked up due to a momentary deenergization of the line circuit. For a further detailed description of this field station apparatus attention is directed to our patent above referred to.

Ojfice telephone apparatus Referring again to Figs. 7A and 73 when laid one above another, the apparatus and circuits shown in light lines therein conform precisely to the apparatus and circuits shown in Figs. 2 and 3 of our said patent, except that the change relay CH2 and its associated code determining relay CD2 have been omitted. In place of these relays CH2 and CD2 have been substituted the telephone change relay CHTI and the telephone code determining relay CDTI. This telephone code determining relay CDTI has also been provided with a code repeater relay CDTPI. The office apparatus is also provided with a telephone code initiating relay SRB and a telephone coding relay SRA. These relays SRA and SRB are controlled by any one of a plurality of telephone code determining repeater relays, such as relay CDTPI for instance, supplemented by one or more telephone coding keys, such as key KIA. The office apparatus has also superimposed thereon in addition to the apparatus disclosed in our said patent a buzzer BUZ, an office filter FILO and a telephone TELO including a receiver Re and a transmitter T1.

The new circuits that have been added to the oflice apparatus to constitute the present invention include a special hold-over circuit for the relay OC including front contacts 518 and 589 of relays CDTPI and SEE in multiple and front contact 519 of relay SB; a special hold-over circuit for the pulsing relay NC including front contact 421 of relay LV and front contact 581 of relay CDTI; and a special hold-over circuit for the relay E including front contact II4 of the relay. LV, front contact 590 of the relay CO, wire 59I, front contacts 588 and 591 in multiple of relays SRB and CDTPI, wire 596, and front contact II9 of relay VP. There are also other additional circuits, such for instance as, the telephone coding circuit including front contact 6M of relay CDTPI, back contact 602 of relay CDTI, front contact 603 of relay SRB and coding contact 604 of relay SRA, for energizing the pulsing relays PC and NC.

Field station telephone apparatus Referring again to Figs. 70 and 7D it is now proposed to describe the apparatus that has been superimposed on the C. T. C. field station equipment illustrated in our said patent. All of the apparatus which is supplemental to that disclosed in Figs. 5A and 5B of our said patent has been shown in heavy lines in Figs. 7C and 7D of the instant application.

Referring to Figs. 7C and 7D when laid side by side the relay IF has been illustrated as a double winding relay instead of the single winding relay IF illustrated in our patent and just to the left of this relay has been illustrated a telephone TELI connected in series with the cone denser CI across the line wires III-I8. Although no particular apparatus has been shown in Figs. 70 and 7D for ringing the bell associated with the telephone TELI located directly; at the field station shown in these drawings it is proposed that a telephone bell may be sounded by the picking up of a neutral relay connected in the circuit and controlled in a manner similar to the manner in which the switch machine control relay SlVER. has been shown connected and controlled and to provide a bell energized and sounded through a front contact of such relay. In other words, in order to establish telephone conversation with a man located .directly at the field station it is proposed to call such attendant to the telephone through the medium of a polarity code such as is used for controlling a switch machine or a signal and witlrout the employment of a telephone coding key or a telephone selector such as conventionally illustrated at SIA and as shown in Fig. 3, and as will be described hereinafter.

Bridged across the line Wires I8 and I8 at the field station shown in Figs. 70 and 7D is a telephone transformer Tl which is of the usual construction. A condenser C2 is used at a mid-point in its primary winding and a condenser C3 at a mid-point in its secondary winding to block out the coded direct current. The secondary winding of this transformer TI is connected directly to the line which leads to a distant telephone location at which the telephone selectors SIA and SIB (see Fig. 1B) are located. The tele- Phone line 81A and SEE is also fed from a relaying unit This relaying unit RUI relays the telephone code, which is transmitted from the ofiice to the field station through the medium of the centralized traffic controlling system, from the contact 505 of line relay IF to the distant telephone selector units SIA and SIB; this relaying unit RU! being selected by the telephone station selecting relay ISOT. This relaying unit RU! comprises a battery 502, a coding relay FRA I and a code initiating relay FRBI, together with a suitable filter FILI similar to the filter FILO at the central oflice (see Fig. 713) comprising inductors 1 1 I and I capacitors or condensers C4 and C5 and resistors RI and R2 all arranged in the manner shown to provide what is known'to the art as a low pass filter.

The code initiating relay FRBI is a direct repeater relay of the telephone station selecting relay 1SOT, it being energized directly through 2. front contact 583 of this relay ISOT. The coding relay FRAI is energized through a circuit including the polar contact 505 of the line relay IF and the front contact 586 of the telephone station selecting relay ISOT in series, so

that this telephone coding relay FRAI is picked up each time that the C. T. (3. line circuit Ill-48 is energized by current of positive polarity so long as the station selecting relay ISOT is energized. This station selecting relay ISOT will be energized only if that field station has been selected by having its stepping relays operated through the entire cycle and to the point where the last stepping relay LV is energized. This circuit for the telephone station selecting relay 'ISOT may be traced from the terminal of a suitable source of current, front contact 50l of the stepping relay IN (the front contact I25 of the relay 850 having dropped by opening of contact M4 when the relay LV is picked up),

the polar contact 38 of the line relay IF assumingleither its right-hand or its left-hand position, the front contact 428 or 429 of relay LV, dependingupon the polar position then assumed by the line relay IF, through the winding of the leading to the telephone selectors telephone-station selecting relay .ISOT. This station selecting relay ISOT issufficiently slow dropping so that it will not be dropped during deenergization by pole changing of the C. T. C. line circuit resulting in movement of the contact 38 of the relay IF from one extreme to the other extreme position.

Another addition to the field apparatus of Fig. 7C and 7-D above that of the disclosure of our prior application resides in the provision of double contacts on the relays ILO and IE in the line circuit to make or break, as the case maybe, the line circuit in both wires l8 and I8 at the same time. This function is performed by contacts 145 and 546 of relay ILO and contacts 258 and 588 of relay IE. When the lockout relay I'LO is energized the line circuit may be intermittently closed by the pulsing relay IE through the shunt path including the inductances I8 and I9 and the resistance R8 in series. The resistance R8 has an ohmic value substantially equal to the resistance of that part of the line circuit for which it issubstituted and the reactance of the inductances I8 and I9 although they do not materially restrict the flow of direct current they do attenuate the flowof currents of audible frequency between line wires 18 and I8 when contacts 588 and 258 on relay E are closed during coding of the linecircuit by that field station. The resistance RI3 and condenser C13 in series are bridged across the line wires adjacent the inductances I8 and '19 so that they in combination with these inductances may comprise a filter and also may serve to smooth out the impulses created when theline circuit is pulsed by the pulsing relay IE.

As shown, under all conditions except when field'station No. 1 is transmitting an indication the condensers C8and CM- as well as condensers C9 and C15 are connected in multiple, respectively. This multiple grouping of these condensers results inr'ather large capacity units around the windings of the line relays at the field stations so that in spite of a large number of these units inseries the voice frequency currents can still flow freely. During the transmission of an indication from a particular field station-as forinstance from the field station No. l, the contacts 534 and 535 are open and result 'in'. disconnection of the condensers CM and CIS from the line circuit. Although with the condensers CM and CH removed from the line circuit the flow ofvoice current is some-' what restricted. This restriction is comparatively small because this takes place at only one field station at a time, as a rule at least. In practice the capacity of the condensers C14 and Cl?) is about twice that of condensers C8 and C9 as a result of which the capacity at this point is reduced to one third upon picking up of the lock-,outrelay lLO. The real purpose for reducing the capacity included in series in the line circuit Ill-l8 beyond the field station that is then sending is to avoid the impulses created by the pulsing relay E at such field station from passing to more distant field stations in suificient quantity to cause operation of line relays at such more distant stations.

Telephone calling key The telephone selector system superimposed upon the centralized traffic controlling system of our said patent comprising the present invention is the well known Western Electric dispatchers telephone selecting system which is disclosed in the patent'to Field No. 1,343,256 dated June 15, 1920, and the telephone key illustrated in Fig. 2 of the drawings in a conventional illustration of the key disclosed at the left-hand end in Fig. '7 of said Field patent.

Briefly stated, this telephone coding key KIA includes a coding contact 5) and a code initiating'contact 5, a coding wheel 5| 2, a ratchet clockwise direction by aspring 522 and having a pawl 523 for engaging the notches of the ratchet Wheel 5l3, the shaft'529 being connected to'and driven by the gear 514. The movable portions of the coding contact 510 and the code initiating contact 5 are pivotally supported by a shaft 525 which shaft is biased in a clockwise direction by a spring 526 to cause the cam 521 tobe held'against the stop 528. It will be readily seen that as the coding wheel 5|2 is rotated in a clockwise direction that the cam 521 may be lifted to either an intermediate point to close the code initiating contact 5| l or may be moved to a higher poin'tto also close the coding contact 5). The net result is that during each revolution of the coding wheel 5l2 the code initiating contact 5 is closed through substantially the entire revolution of the coding wheel, whereas the coding contact 5l0 is intermittently closed to characterize short impulses in accordance 'With the number of teeth on the coding wheel 512 which are not covered by the guards 539 or 53 I. For the particular coding wheel illustrated it is readily seen that the coding contact is closed eight times during one revolution of the coding wheel 5I2 of which the third closure, the sixth and the eighth closure are long, whereas the remaining five closures are short, so that by reason of the fact that each closure results in the picking up of the relay PC and each opening results in the picking up of the relay NC the code consists of nine negative impulses separated by eight positive impulses of which the sixth and the twelfth and sixteenth impulse are long impulses of positive polarity and of which impulse sixteen is extremely long. It should be noted that the first impulse due to closing of contact 5! I and in turn contact 693 of relay SRB produces no effect in that the negative pulsing relay NC is already energized. That is, front contact 593 of relay SRB closes before front contact 581 of relay CDTI. opens so that no change in line circuit current due to the closing of the impulse circuit at front contact 603 takes place. The code character created thereby is therefore 5-6-4, because the effective fifth, eleventh and fifteenth impulse are long.

In Fig. 1A of the drawings four such coding keysiK'lA, KIB, KZA and KZB have been conventionally shown. The codingkeys KIA and KIB must be adjusted to transmit different codes since they are used for selecting and ringing two different telephone bells at or branched from the same field station. Since keys KZA and KZB select telephones at a different field station they, although they must transmit codes differing from each other, may transmit respectively the same codes as are transmitted by keys KIA and K'IB.

Telephone selector and associated telephone apparatus .In' Fig. 3 has been illustrated a typical telephone selector unit SIA of the type disclosed in the Field patent above identified; whereas essential parts. of this selector have been illustrated in three diiferent stationary positions in Figs. 4, 5 and 6, respectively.

Stating it briefly this telephone selector comprises a ratchet wheel 549 directlyconnected to a contact carrying pin wheel 54!, this pin wheel 54! being biased in a clockwise direction into the normal position, in which position it has been shown in Fig. 3, by a suitable coil spring (not shown). Associated with the ratchet wheel 540 is a ratcheting arm 542 carrying a driving ratchet pawl 5'43 and a holding ratchet pawl 544, this ratchet arm 542 being pivoted at 545. Directly below the ratchet wheel is a polar armature 541, pivoted at 548, and adapted to be moved from one extreme position to the other extreme position from its neutral biased position, shown in Figs. 3 and 6, depending on the polarity of the current. To this armature 541 is connected an S-shaped operating arm 55!] provided with pins 55! and 552, these pins being so located that if the armature 541 moves the S-shaped arm 550 in a clockwise direction the ratchet arm 542 is moved in a counter clockwise direction as is also true if the armature 541 is moved in a counter clockwise direction. In other words, for each operation of the armature 541 from normal, either to the right or to the left, the ratchet arm 542 is moved to the left against the normal bias of the spring 554. It is readily seen that by this construction oscillation of the armature 541 in opposite directions from its normal position about the pivot 548 will cause rotation of the ratchet wheel in a counter clockwise direction so as to be advanced one ratchet tooth corresponding to one pin hole for each energization of the. electromagnet 549. This code selector also includes a holding spring 556 located out of the plane of pins 551, 558 and 559 located in the contact carrying pin wheel 54l so that these pins can freely pass by this holding spring 556. The end of this spring 559 is, however, provided with a projecting saddle 559 which is located in the plane of these pins 551, 558 and 599 but normally (see Fig. 3) lies to the left of the circumferential path through which these pins 551, 558, and 559 move during rotation of the pin wheel 54!. During intermittent operation of the armature 541, and the ratchet arm 542 intermittently operated thereby, the saddle 560 vibrates at some position to the right of the pins and pin holes but does not get time to reach its full deenergized position shown in Figs; 3 and 6, but upon deenergization of the electro-magnet 549 for an appreciable time the saddle 559 is moved toward the left. If there is then a pin in the path of movement of this saddle toward the left the saddle will be arrested by the pin and the saddle will in turn engage the pin and prevent return of the ratchet wheel 5491 to its normal biased position as shown in Fig. 6, but if there is no pin in the path of the movement of the saddle 569 it will return to its normal biased position as shown in Fig. 3. As illustrated the pins 551, 558 and 559 are located in the fifth, the eleventh and fifteenth hole to conform with the code which will be set up by the coding key KlA heretofore described and illustrated in Fig. 2 of the drawings. This holding spring 555 is operated by being engaged by the roller 542 pivoted to the :lower end of the ratchet arm 5.42.

If .now the coding key of Fig.2 were to control the selector illustrated in Fig. 3 the operation of the code wheel 53l (seeFig. 2) would produce a 3 code of sixteen impulsesin the lin circuit I -18 of which the .fifthand eleventh and the fifteenth impulse are sufficiently long to allow full charging of condenser C1 and deenergization of the .electro-anagnet 5 19 for a long period. A long imppulse will :cause a momentary energization followed by .a long. deenergization of the magnet 549 because this electro-magnet 5-19 has included in. series therewith the condenser C1. As soon as the condenser :01 becomes fully charged the :current through the magnet 5A9 ceases to flow causing deenergization thereof. It is thus seen that were 'it not for the pin 551 located in the fifth hole in the pin wheel 54! the ratchet wheel .andthe associated pin wheel would be returned :to" their normal biased zero position during the iong deenergization of the electro-magnet 549 during the fifth and long impulse of the code, it "being understood that both the operating pawl I543and theiholding pawl 544 aredisengaged from the teeth of the ratchet wheel 540 during deenergization of the electro-magnet 549 (see Figs. 3.21161 6). It is, of course, understood that during quick movement of the armature 541 of the Ielectro-magnet 549 from one extreme through its intermediate biased and to the other extreme position will not allow the ratchet wheel or its associated pin wheel to return toward normal .due' to the inertia of these wheels] It is thus seen that the code selector illustrated in Fig. 3 will not 'be allowed to return to its biased position during the long fifth, eleventh and fifteenth impulse of the code, and it should also be understood that there may be many other code selectors connected inmultiple with the one shown in Fig. 3 in which the pins 551, -553and 559 are located in different holes than the fifth, eleventh and fifteenth hole-because they have been adjusted to respond to different codes, and therefore the code wheels of these other selectors will be returned to their normal biased position during one or more of the long fifth, eleventh or fifteenth impulses. Since any code wheel that has been returned to its normal position during a long impuls during an intermediate part of acode will not reach its extreme bell ringing .position when the total number of fifteen impulses have been transmitted, .it is evident that only the cod wheel which has its pins located to characterize the same code as the code transmitted will ring a bell. Page 5 of the Field patent above referred to conta ns a table of all of th possible codes for a fifteen impulse code telephone selector system. 'The ratchet wheel 540 is provided with .a radially projected arm 562 insulated from the wheel and provided with a contact 563 connected as by a pig tail to a wire 564 leading to the negative pole of a battery 551. This contact 553 is adapted to engage a stationary contact 565 when the pin wheel has been rotated to its fifteenth hole position to close a circuit including the coils 556 of the telephone bell andincluding th battery 561. The sounding of this bell 5539 will of course call the attendant to the telephone which has been conventionally illustrated by the receiver Re and the transmitter Tr. This telephone Re-Tr is rendered effective as soon as the receiver Re is removed from the hook 558, resulting in the closure of one circuit through the transmitter Tr,

including the condenser C12, receiver Re and the secondary winding of this transformer in series across the telephone line.

Operation Referring to Figs. 1A and 1B of the drawings let us first assume that an operator at the ofiice illustrated in Fig. 1A desires to operate the track :sWitGh (shown in Fig, 7D) located at field station No. 1 shown at the left in Fig. 1B. To accomplish this he moves his switch machine lever SMLI into its right-hand dotted position, thereby connecting the wire leading from the switch machine lever SMLI to the negative line impulsing :relay NC instead of to the positive impulsing relay PC. This in itself however does not produce any results because the two circuits leading from the switch machine lever SMLI are open at front contacts 13 and 586 of the code determining relays (,Dl and CDTI. Let us now assume that the operator depresses the push button Bl resulting in the closure of contact 38 and the energization of the change relay 'CI-I-l, the change relay CI-Il being obviously energized through a ,pick-up circuit including the contact 39 of the cancelling push button CN'B. With this relay 'CHl once energized itwill be energized thereafter through a stick circuit including the back contact 49 of the code determining relay CDI. If there is no other change relay CHI energized at this time the code determining relay CDI will be energized through a circuit including back contact M of relay SC, back contact 42 of relay CF, back contact 43 of series relay CDS, back contact 510 of relay (ii-1T2, back contact M of relay CH2, back contact '51! of relay CHTl, front contact d5 of relay CHl, the upper winding of relay CD 5 ,and contact 39 of the cancelling button CNB. With code determining relay CD! energized it will remain energized through a stick circuit including rba ck contacts 66, as and 49 of the relays LV, CO and SC, respectively, in multiple, winding of the series relay CDS, stick contact 41 of the relay CDI and contact Lt-9 of the cancelling button CNB.

Picking up of the series relay CDS by the com- 'pletion' ofthe stick circuit just traced will prevent the field startingrelay CF from being picked up through back contact 5| of the relay CDS, back contact I of the relay F and front contact I95 of the relay OR (see Fig. 7A), and will instead pick up the office starting relay CO through the medium of its front contact 51 and the back contacts 56 and 52 ofthe' relays SC and CF. With the relays ODS and CO'now energized the stepping relays Vi, V?., V3, V5 and LV will be successively picked up in a manner as described in 'our'said patent and will thereby cause the contacts .64; E3 and 62 of the stepping relays to applycurrent to one or the other of the pulsing relays PC and N C depending upon the fixedly adjusted position of the jumpers $1, 19 and 12. Upon picking up of the fourth stepping relay V4 the front contact El will cause energization of a pulsing relay PN or NC depending on the con- 'trol impulse to be transmitted which in the present instance is the pulsing relay NC, and through a circuit including front contact El of the stepping relay V4, front contact is of the code determining relay CDi, contact it to the switch machine lever SMLI assuming its right-hand position'. i

At the field station (see Figs, 1B, 7C and VD) the first three successive impulses just transmitted to the field station will cause the station selecting relay ISO -(see Fig. 70) to be maintained energized through front contacts I24, I23 and 32 of the relays VI, V2 and V3 in that order as is determined by the code jumpers I40,

MI and I42 shown in Fig. 7D. On the fourth step, namely, when the stepping relays V4 at the control ofiice and at the field station No. l are both energized current of negative polarity is transmitted over the line circuit, as determined bythe position assumed by the switch machine tion of the switch machine SM to its reverse position. During the last step of the code cycle, it being of course understood that in practice a largernumber of controls and indicators would be involved than can be accomplished by the five stepping relays illustrated, the stepping relay LV is energized and by lifting of its contact I44 will condition the stick circuit for the station selecting relay so as to be dependent upon front contact 29 of relay ISB and back contact I38 of relay IFA, so that as soon as the line circuit is deenergized long enough to cause dropping of the cycle marking relays ISA and ISB relay ISO will release. If relay IFA is, however, picked up in the meantime station selecting relay ISO will release before cycle marking relays ISA and ISB release. 'In the office the picking up of the relay LV on the last step of the C. T. C. code by the opening of its back contact 46 breaks the stick circuit for the code determining relay CDI causing dropping of this relay and further causes dropping of the cyc1e marking relays SA, SB, so and SD.

' Let us now observe how the apparatus functions when it is desired to operate one of the telephone selectors'SIA or SIB located at field station No. 1 to call an attendant to the telephone. Referring again to Figs. 1A and 1B, if the operator wishes to establish telephone communication with an attendant located to have access to telephone and selector SIA either with 'or without changing the position of a control lever for that panel he will depress the telephone push button BTI, thereby causing energization of the change relay CHTI. This change relay when once picked up will be stuck up through a stick circuit including its own front contact 514 and the back contact 515 of the code determining relay CDTI. If no other change relays are'then energized the code determining relay CDTI is energized through a circuit such as heretofore traced for the code determining relay CDI except that it includes the front contact 51I of the change relay CHTI. With this code determining relay CDTI picked up a stick circuit therefore is closed including its own stick contact 576, the winding of the relay CDS, and back contacts 46, 48 and 49 of the relays LV, CO and SC, respectively, in multiple. The picking up of the code determining relay CDTI also causes energization of the code determining repeater relay CDTPI through the front contact 511 of the relay CDTI. With the code determining repeater relay CDTPI picked up it closes at its front contact 518 an energizing circuit for the relay OC as soon as the cycle marking relay SB has been pickedup to close its front contact 519.

This circuit including contacts 518 and 519 performs no particular function at this time, but it prevents the clearing out of the office coding apparatuswhen a long impulse is applied to the line circuit as will be the case if the operator allows the buzzer to sound for a long time or for reasons explained hereinafter. With the series relay ODS and the relays CO and 0C controlled thereby now energized the oflice apparatus will cause a code to be applied to the line circuit Iii-I8, all in a manner as determined by the code jumpers 589, 58I and 582 rendered effective through front contacts 583, 584 and 585 respectively, insofar as the first three impulses of the coding cycle, which are the same as when. the code determining relay CDI was energized, are concerned. During the fourth impulse the polarity of the impulse will be determined by the circuit including the front contact BI of the relay V4, the front contact 586 of the relay CDTI, and the position then assumed by the switch machine lever SMLI. In other words, the coding cycle transmitted to the field station when it is desired to establish telephone communication will be exactly the same as when apparatus at such field station is to be controlled up to and including the second last impulse of the code cycle. That is, the apparatus at that field station will be recontrolled in accordance with the positions assumed by the switch control and signal control levers at the ofiice. When the last impulse is transmitted to the field station, namely the impulse that flows when the last stepping relay LV is energized, a special circuit, including the front contact 421 of the stepping relay LV in the ofiice and including the front contact 581 of the code determining relay CDTI, for the pulsing relay NC is closed. This circuit transmits a negative impulse and will remain closed until the operator has operated one of the coding keys KIA or K! B to transmit a telephone selecting code. This long impulse of negative polarity may continue for a very long time depending upon'the alertness of the operator. 7

The operator will be apprised of this long last impulse of the C. T. C. code by the sounding of the buzzer BUZ, which is sounded through the following circuit: beginning at the terminal of a suitable source of current, front contacts H3 and I20 of the relays CO and CF, in multiple, front contact II4 of the last stepping relayLV, front contact 599 of the relay CO, wire 59I, back contact 588 of the code initiating relay SRB,

Wire 595, and front contact 592 of the line repeater relay FA, through the winding of the buzzer BUZ and to the other terminal of said source.

During this sounding of the buzzer BUZ and during the remaining portion of the combined C. T. C. and telephone code cycle the relay VP is maintained energized continuously through the front contact I08 of the stepping relay V4 (see Fig. 7B) and with the relay VP and the relay LV both energized, it being understood that the relay CDTPI is also now energized, an energizing circuit is closed for the relay E which may be traced from the terminal-(+), through the front contact II3 of the relay CO, front contact II4 of the relay LV,'front contact 590 of the relay CO, wire 59I, front contact 591 of the relay CDTPI, wire 596; front contact II9 of the relay VP,through the winding of the relay E to the other terminal of said source, so that this relay E remains energized to the end of the combined C. T. C. and telephone selecting and ringing cycle.

In addition to the stick circuit for the relay CDTI including the stick contact 516 heretofore traced there is a second stick circuit for this relay CDTI which includes the stick contact 593 of this relay CDTl and the back contact v594 of the relay 'SRB. The picking up of the last stepping relay LV at the office by the opening of .its back contact 46 breaks the first stick circuit for the code determining relay CDT! including the stick contact 516.

At the field station No. 'l the last stepping relay LV is also in its energized condition because the station selecting relay ISO ,(see Fig. 70) was still energized when the fourth stepping relay V4 became energized, but the last stepping relay 'LV at all other field stations will not be energized because the stepping relay V4 at such other field station did not become energized. At station 1, therefore, the last stepping relay LV closes the following energizingcircuit for the station telephone selecting relay lSOT: beginning at the terminal (-1-) of a suitable source of current, front contact 5m of the relay LV, contact 30 of the line relay IF assuming its left-hand position, front contact 429 of the relay LV through the winding of the relay ISOT to the other terminal of this source. Picking up of the telephone station selecting relay ISOT also closes an .energizing circuit for the code initiating relay .FRBI which includes the front contact 503 of the relay lSOT. With the telephone station selecting .relay ISOT energized and its front contact .506

closed an energizing circuit will be closed for the telephone coding relay FRAI at one point, this circuit however being open at the contact 595 of the line relay IF in its left-hand positive polarity position.

Referring now again to the apparatus in the ofiice, it being remembered that the buzzer BUZ is still sounding, let us assume that the operator in response to this sounding of the buzzer operates his telephone key KIA. Referring to Fig. 2 this operation of the telephone key KiA resides in movement of the lever 521 to the horizontal position at which point the pawl 523 engages the next tooth of the ratchet wheel 513. Upon .release of the handle 52| it will be gradually returned to its initial position, against the stop 524. This return of the lever 52l to its initial position operates the coding wheel '5l2 through one complete revolution. During the larger part of the rotation of the coding wheel 5H2 through one revolution the code initiating contact 5. (see Figs. 2 and 1A) is continuously closed, and although the closure of this contact results in energization of the relay SRB and closure of the contact 603 in the circuit for relay NC this vdoes not produce an impulse because relay NC was already energized. Thecoding contact 510 is later intermittently closed to characterize a code of fifteen impulses of which the fifth, the eleventh and the fifteenth impulse, created by the third, sixth and eighth tooth respectively, are long. The first two of these long impulses are due to the guards 530 and 53! each making three teeth of the coding wheel equivalent to one long tooth, and the third impulse is due to the uncut part of the coding wheel 5l2.

Referring now to Fig. 1A it will be observed that closing of the code initiating contact 5! I, the front contact 553 of the code determining repeater relay .CDTPI being closed, closes an energizing circuit for the code'initiating relay SRB.

Thepickinggup :of the relay SRB closesa stick circuit for :the code determining repeater relay CDTP-l at the front contact: 594 of the relaySR-B whichincludes the front stick contact 599 of .the relay CDTPL This lifting of the contact 594 of the relay SRB-opens one stickcircuit for the code cleterrn'iningrelayCDT-l at back contact 594, the other stick circuit for thisrelay being open at all of the :backcontacts 46, 4.8 and 4.9 of the relays LV, C10,..and SC respectively in multiple. The pickingup of the codeini'tiating relay SRB closes at its front contact 1603 a second circuit for the negative pulsing relay PC but this circuit is .still open .at back contact 602 .of relay CDTI. The code determining relay CDT! is deenergized by the opening of its second stick circuit including stick contact 15193, and :by the opening of its contactr58i wouldremove the long impulses from the line circuitllJ-Hi were it .not for the new circuit for relay NCincluding back contact 602 of relay CDT-l. This new circuit allows the pulsing relays PC .and NC to be controlled to transmit the telephone code to thefield station by intermittent operation [of the telephone code transmitting relayiSRA. In other words, intermittent opening and closingofrthe-coding contact-510 of the coding key KIA :causes intermittent energization of the code transmitting relay :SRA through a circuit including .the-front-contact-BM of the'relay SRB, and intermittent operation of the code transmitting relaySRA due to the intermittent closure of its energizing circuit just traced causes alternate energization of the pulsing relays PC and NC through the following circuit-beginning at the terminal of a suitable source of current, front contact GM of the relay CDTP'I, back contact 1002 of the relay CDTI, front contact 50B of the relay SRB and the front or the back,.as thecase may be, contact 604 of the relay SRA. This intermittent operation of the telephone .code transmitting relay SRA therefore transmits two impulses, for each energization'of the relay SBA, that is, transmits eight impulses of positive polarity interspersed by seven impulses of negative polarity making a total of fifteen impulses of which the fifth, eleventh and fifteenth impulse of the positive polarity .are long.

Referring now to Fig, 1A of the drawings, these impulses cause operation of all of the polar line relays, such as relays lF and 2F to alternate energized positions remaining in such positions for longer-times during the long impulses. Since, however, .only the telephone station selection relay .tSOT is energized the telephone code will only be transmitted to the relay unit RUI (Fig. 1B) resulting in intermittent energization of the coding relay .FRAI. This telephone code will then be retransmitted to line wires .605 and 601 through the medium of pole changer contacts Eilxand 6|2 of the relay coding relay FHA! and through .front contacts 6|3 and 614 of code initiating relay FRBI. The first five impulses transmitted .toselector .SlA -(-see Fig. 3) will ratchet the ratchet wheel .540 to a position where the first pin 551 is in alignment with the saddle 560 fastened to the end of the holding spring 556. Since this fifth impulse is long and since the circuit for the electromagnet 549 includes a condenser Cl, the condenser will after the usual impulse time have been fully charged and the flow of current will cease during the remaining part of this long impulse, as a result of which the .S-shaped arm 550 is returned to its neutral position shownin Figs. 3 and .6 allowing the ratchet arm 3542 to assume its normal biased position under whichconditioriboth the actuating pawl 563 and the, holding paw1544' will be out of engagement'with the ratchet wheel 54!) and the holding spring 555 would be allowed to be moved to its normal extreme left-hand position as shown in Fig, 3, were itnotior the pin551 which it engages (see Fig.- 6), thereby preventing the return'of this pin wheel 5 to its normal biased position. All of-the various selectors which do not have five (a pin in fifth hole) for their first digit will return to their normal position. In a similar manner the eleventh impulse which is also long will have resulted in rotating the pin wheel fi li to a position where the pin 558 is engaged by the saddle 550. Since there is only one selector left, namely, selector S IA, which has six for its second digit all but this selector SI A will-have returned to their normal position at least once at the end of the second digit of the particular code. The next four impulses, namely-the impulses of the third digit will advance the ratchet wheel of selector SIA and its associated pin wheel 54! to fifteenth hole position where the contacts 563565 close to ring the telephone bell 569. Since this fifteenth impulse is long to the extent of the circuit portion of the code wheel 5I2, the saddle 560 will engage the third pin 559. Duringthis four impulse digit of which th'e'last impulse is longother selectors will have their pin wheels 5M advanced and others will have them restored tonormal but since every selector'except selector SIA has lost at least one step, by having been restored to normal at least once during the code, none of these other selectors will have advanced far enough to close their contacts 563565.

The coding key code wheel 5I2 makes the fifteenth impulse by closing of its contact 5"). The opening of the "contact 5 IE1 at the end of the ringing time causes a sixteenth impulse by dropping of the relay SBA which in turn causes the transmission of a negative impulse over the line circuit and operation of contact 505 of line relay I F to the left and dropping of relay FRAI. This results in the sixteenth impulse which kicks the saddle 5% away from pin 559 and allows selector SIA as-well as any other selector that has not yet returned to normal, to return to normal. Also, when the arm 521 drops in the notchv of the code wheel 5I2 the contact 5| I is opened resulting in deenergization of the relay SRB resulting in deenergization of the relay CDTPI by reason of the opening of its stick circuit at the front contact 594 of the relay SRB. The dropping of the code initiating relay SRB by openin; of its front contact 693 results in the de-' energization of both of the pulsing relays PC and NC as a result of which the C; T. C. apparatus clears out by the dropping of the cycle marking relays SA, SB, SC and SD and the relays controlled'thereby in the control office, which in turn results in the dropping of the cycle marking relays ISA and ISB at the field station to cause the C, T. 0. apparatus to return to its normal line energized condition.

In a manner similar to that just described the depression of the telephone push button BTZ will, through the medium of the change relay CHT2, energize the code determining relay CDTZ and the code determining repeater relay CDTP2. This will through the medium of the code communicating system result in the energization of the telephonestation selecting relay ZSOT at fieldstation-No. 2 shown in Fig. 1B of the drawings; This will allow' the telephone selectors SZA and- SZB to be controlled by the telephone keys KZA and KZB, respectively, in a manner similar to that just described. In this connection it may be pointed out that all of these telephone selectors SI A, SIB, 32A and SZB are identical except that they have their coding pins 557 and 558 located in the proper holes to characterize the proper code. Similarly, these telephone calling keys KIA, KIB, KZA and K2B are identical except that they have by the guards 530 and 53I been set to characterize different codes, Referring to Fig. 2 it will be seen that the guards 536 and 53I may be adjusted to any desired position by the loosening of the cap screw 606 and by rotating these guards about the axis of the code wheel 5I2 so as to cover certain three tooth groups ofteeth to produce a long impulse, after" which the cap screw 668 may be again tightened up. Attention is directed to thefact that the codes for coding keys KIA and K2A, for instance, may be setto transmit the same telephone code to a distant field station without interference. This, is true because the telephone key KIA can only transmit a telephone code to field station No. 1, whereas the telephone key KZA can only transmit a telephone code to field station No. 2, this being true because the telephone station selecting relays ISOT and 280T can only be energized. at a time.

A telephone conversation transmitted by current of voice frequency can be carried on between the telephone TELO located at the oifice and any one of the telephones located at thevarious field locations at any time, but since the operator has only called one particular telephone the probability is that the attendant at that location only will be in communication with the operator. Also, there is no need of apparatus for a field station attendant to call the operator at the central office because the operator will either have a head set receiver to his ears or will have his telephone connected to a loud speaker so that any field station attendant may speak to him at will without first ringing a telephone bell. As already pointed out the telephone TELI and TELZ located directly at the field location, rather than on some telephone branch extending to some other ofiice as is conventionally shown by the telephone selectors and associated telephones SIA, SIB, SEA and 823, may have an attendant called thereto through the medium of a telephone bell sounded by the momentary energization of a neutral relay controlled in a similar manner as relay SMR (see Figs. 13 and 7D) is controlled.

This. telephone communication between the operator at the OffiCe and any one at the various field telephones may be carried on even though the centralized trafiic controlling system is then transmitting codes for controlling switches and signals or is transmitting telephone calling codes for sounding the bells at other telephones in a manner as just described, without annoyance due to the code impulses on the line circuit. This is accomplished by the employment of suitable filtering apparatus including a filter FILO located between the telephone set and the coding contacts in the control oflice, and similar filters used in each of the relay units RU as Well as inductors, resistors and condensers at the field locations Which also function as filters. This filter FILO is constructed similar to the filter FILI constituting part of the relay unit RUI at field station No. 1, and already described, and for this reason like reference characters have been ap,

plied to like elements of this filter. It may be pointed out that the units of capacity and resistance in series are used to absorb and dissipate high frequency audible pulses created by the pulsing relays PC and NC, the inductances I I I and I being employed to prevent these audible frequencies created by these contacts of the impulsing relays from reaching the telephones TELII, TELI, TEL2 by having these audible frequencies greatly attenuated. Not only may control codes be transmitted for controlling switches and signals during a telephone conversation, but a field station may also transmit an indication code to the control office without impairing the clearness of the telephone conversation. It is, of course, understood from our said patent that before the transmission of a code indication from a field station to a control ofiice can take place a lock-out relay such as LOI (see field station No. 1, Fig. 1B) must first be energized, after which the coding is accomplished through the medium of the relay IE. This lock-out relay LOI terminates the line at that field station insofar as the flow of direct current or pulsating current of low frequency is concerned, but the telephone conversation will be shunted around this field station through the medium of suitable by-pass means conventionally illustrated by the condensers C8 and C9.

It will be noted that when field station N0. 1 transmits an indication code, consisting of impulses varied in. length separated by time spaces varied in length through the medium of its impulsin relay 5E, that this coded current fiows through the resistance R8 included in series with inductances I8 and I9. This resistance R8 is of substantially the same ohmic value as the resistance of that part of theline circuit I9-I9 which has been excluded from the line circuit as now used. The inductances I8 and I9 are employed to substantially block, and to a large extent prevent, the flow of telephone current through this shunting branch I3, I9 and R6. The inductance in this shunting branch is divided into two parts I3 and I9 to maintain the impedance balance heretofore mentioned and these inductances are located to the left of contacts 253 and 648 so that disturbances generated by the opening of these contacts cannot easily reach the telephone TELI.

At'the last field station this line substitute R8 I 13-49 is not necessary since no line circuit including more remote field stations has been'excludcd. At this station No. 2 the condensers C8 and C9 have also been omitted. The lifting of the contacts of the lock-out relay L02 will not in any way change the inductance or resistance of the line circuit, it merely including the contacts of the pulsing relays 23:1 in series in the line circuit. The telephone transformer T2 has its primary winding connected directly in the line circuit through the condenser CH and at all times permits the flow of telephone audible currents through the primary winding thereof but the coding currents cannot fiow through this primary winding. The secondary Winding of this transformer T2 is provided with a condenser CI2 therein to prevent the coding impulses impressed upon line I6I9 from being audibly noticeable in the telephone circuit 6I6-6I8 leading to the telephones and selectors SEA and S213 connected thereto and also to prevent the battery current, at times applied from battery 562 to the line wires 646 and 6I6, flowing through this secondary winding.

In addition to the contacts already referred to in the specification there are numerous other contacts the purpose of which has been described in our said patent, in View of which it would seem unnecessary to describe the function of these additional contacts.

Referring to Figs. 7A and 7B, the line relay F is provided with contacts I4, 2|, 24, 15, 18, I95, 266, 262, and 265. Relay FA is provided with contacts 19, 86, 9I and 592. Relay PC is provided with contacts I6, 20, 11 and 42L Relay NC is provided with contacts I5, I1, I9 and 422. Relay E is-provided with contacts 69, I98, 296, M2, M8. Relay EP is provided with contacts .268 and 215. Relay VP is provided with contacts 88, 89, 92 and I I9. Relay VI-is provided with contacts81, 66, I66, -I-6I, and H6. Relay V2 is provided with contacts 94, I62, I64, I415 and 1. Relay V3 is privided with contacts 99, I63, I96, H6, and I45. Relay V4 is provided with contacts 93, I01, I98, I99, and H5. RelayLV is provided with contacts 46, 98, H0, H4 and 42-1. Relay 0C is provided with a contact 56. Relay OR is provided with contacts 29, III, H2, and I96. Relay CF is provided with additional contacts I 3, .23, 42, '52, 65, I26, I91, I99, 2M, 293, 210 and 2H. Relay CO is provided with contacts I2, 22, 48; 54, 58, 16, 91, H3 and 5%. Relay SA isprovided with contacts 23, 55, and 89. Relay SB is provided with contacts 53, EI, 63 and 519. Relay SC is provided with contacts 4|, 49, '59, 66. 15, 62, 85, 96 and 264. Relay SD is provided withcontaets I I, 51, 84, and 213. Relay TON is provided with contacts 212, 291, and M1. Relay TOF is provided with contacts 291, 214, and M3. Relay LOF is provided with contact 216. Relay LON is-provided with a contact 238.

Referring now to Figs. '76 and 7D, relay IF is provided with contacts 36, I29 and 545. Relay IFA is provided with contacts I36, 432, (I34, I36, I51, I65, 2I1, 2-I'8, 226and 245. Relay ISA is proided with contacts I54 and 232. Relay I'SB is provided with contacts 36, I26, I55, I63, I10, I96, I9I, 229, 233, 248 and 4-I'4. Relay IS is provided with contacts I81, 226, 231, and 269. Relay IOC is provided with contacts I35, -I83,-and 221. Relay IL is provided with contacts 35, I21, I85, I92, and 299. Relay ILO is provided with contacts I46, 2I4, 222, 236, 244, 241, 251, 498, 425, and 546. Relay IRL is provided with contacts 31, I28, I84, and I93. Relay ISO is provided with contacts I25, I3I, I33, I31, I56, I64, 216, 22I, 236, 4'I5, and 426. Relay ISOS is provided only with contacts I36 and I39. Relay IE is provided with contacts 243, 253, 259, 26I, and 693. Relay ICE is provided with contacts 21 and I89. Relay ICHP is providedwith contacts I90, I34, 2I5, 228, 235 and 268. Relay IVP isprovided with contacts 466, I62, I61, 234, I, and 254. Relay VI (Fig. 7B) is provided with contacts 34, I24, I59, I12, I15, I16, 2H), 224, 253,262, M9 and 439. Relay V2 is provided with contacts '33, I23, I69, I11, I19, 2H, 23.9 and 252. Relay V3 is provided with contacts 32, 22, I14, I18, 2I2, 25I, and 4.42. Relay V4 is provided with contacts 3!, I2I, I52, I68, I99, 2I3, 249, 2.5.3 and 26,6. Relay LV is provided with contacts I44, I13, I8I, 423, 42-9, 433, and 5M. Relay ILOF is provided with contacts 2I9 an .256. Relay I LON is provided with contacts 246, 263, and 4-!6. Relay T is provided with contacts 26 and Relay M is provided with contacts 25 and 2 Modification Fig..8.-If desired the circuit arrangement for the line relay F, the .polechanging contacts of the relays PC andNC, .Lthe .filterFILO and the contacts 276, 7G, and H2 of the relays CF, CO, and OR, respectively, as shown in Figs. 1A and 73 may be arranged so that these elements are interconnected as shown in Fig. 8. The principal diiference between the structures of Fig. 7B andvFig. 8 is that the windings of the relay F have been divided into two parts and this relayhas been shifted to the line circuit side of the pole changer contacts of the relaysPC and NC and the filter FILO and that the stick contact 2! of the relay F shown in Fig. 7B has been omitted. The reason for inserting the line relay F beyond the pole changer contacts and the filter is in order to use'the inductance of the line relay F as an additional choke to prevent audible frequency surges due to the operation of these pole changer contacts from reaching the telephone TELO located on the line side of the relay F and to place the relay Fat theofiice under line operating conditions more nearly thesame as the line conditions under which the line relays at the field locations operate. That is, the capacitance and inductance of filter FILO modifies the characteristics of the line pulses as they are transmitted through the filter and since it isdesirable in the C. T. C. systemto have all line relays operate in unison or synchronism as nearly as possible all line relays should be placed on the same side of this filter. It will be seen that in the Fig. 8 arrangement the contacts 210, I6, and H2 of the relays CF, CO, and OR, when closed, merely shunt out the resistance unit R; whereas, in the Fig. 73 construction they also shunt the stick contacts 2!, of the line relay F, that is, in

the Fig. 73 construction theline circuit cannot be closed at all while the line relay F is down unless one of the contacts 21]), It, or i i2 is closed; whereas, in the Fig. 8 construction the line circuit may be closed, even though relay F is down, and all of the contacts 218, liiand H2 are open, but if the line circuit is so closed it will be of rather high resistance by reason of the inclusion of the resistance unit R. In other words, the contacts 210, 16 and H2 serve merely as energy saving contacts since when all are open during periods of rest of the C.,T., C. system the line current is substantially reduced. In the Fig. 8 construction, the line relay F as already mentioned is also provided with two windings instead of one, one winding being included in series in each of the line wires. This construction affords a balanced line which is desirable for reasons already pointed out in connection with the line relays IF and ZFshoWn in Fig. 1B. It may also be stated here that if desiredthe line relay F may be of the polar type similar to relays IF and 2F, the contact structure in this event being modified as conditions require.

The applicants have thus provided a compound code system, so to speak, which enables two different types of direct current codes to be transmitted in succession over the same circuit andreceived in part by the same decoding apparatus. It should, however, be understood that even though the telephone selector system has been superimposed on a particular and specifically described centralized traflic controlling system that it may be applied to numerous other code type centralized trafiic controlling systems disclosed in various patents and pending applications assigned to the common assignee. It should also be understood that the specific disclosure of the present invention has been resorted to for the purpose of disclosing the underlying principles of th invention and its functions rather than the specific structures preferably used in practicing the invention, and that numerous changes, modifications, and additions may be made in practicing the invention and without departing from the spirit or scope of the invention except as demanded by the scope of the following claims,

What we claim as new is:

1. In a combined code railway traffic controlling system and code telephone selector system, the combination with a centralized traffic controlling system including a central ofiice and a plurality of field stations, a single line circuit connecting said ofiice and stations, a line relay in said office and at each of said stations controlled by current in said line circuit, a telephone calling coding key at said ofiice, trafiic controlling code transmitting apparatus at said ofiice and traffic controlling code receiving apparatus at each of said field stations and including said line relays for transmitting a series of distinctive impulses from said ofiice to one of said field stations to characterize a station selecting code and including cycle marking relays at each of said field stations which aremaintained energized so long as said line circuit is either intermittently or continuously energized, initiating means at said officeto prolong the last impulse of said series and operated in the event it is desired to transmit a telephone selecting code such last impulse being prolonged until a telephone coding key is operated and to thereby maintain said cycle marking relays energized, means including said centralized traific controlling system and said telephone coding key to transmit a telephone calling code to the selected field station, telephone code decoding means at a field station responsive only if the transmitted code corresponds to the code characterized by such decoding means at such field station and then only if that particular field station has been selected and still has its cycle marking relays energized, and filtering means to allow the flow of voice current around said relays.

2. In a combined code railway trafiic controlling system and code call type telephon system, the combination with a centralized trafiic controlling system including a central office and a plurality of field stations, a single line circuit connecting said office and stations, a line relay in said ofiice and at each of said stations controlled by current in said line circuit, trafiic controlling code transmitting apparatus at said office and trafiic controlling code receiving apparatus at each of said field stations and including said line relays for transmitting a series of distinctive impulses from said ofiice to said field stations to characterize a station selecting code which conforms to the code allotted to one field station and including cycle marking relays at each of said field stations which are maintained energized so long as said line circuit is either intermittently or continuously energized, means at said ofiice including a telephone coding key to transmit a telephone selecting code consisting of a second series of impulses the first impulse of which follows the last impulse of said trafilc controlling series so closely that said cycle marking relays have not had time to drop down, telephone code decodin means at said one field station and including the associated line relay and cycle marking relays and responsive only tothe transmitted telephone selecting code if such transmitted code conforms to the code character of the telephone cod decoding means at such field station and then only if that particular field station has been selected and still had its cycle marking relay energized,

tions, an audible signal in said ofiice, a line relay in said ofiice and at each of said stations all included in series in said line circuit, traffic con trolling code transmitting apparatus at said oifice and trafiic controlling code receiving apparatus at each of said field stations and including said line relays for transmitting a series of distinctive impulses from said office to one of said field stations to characterize a code and including cycle marking relays at each of said field stations which are maintained energized so long as said line circuit is either intermittently or continuously energized, means at said office to initiate the transmitting. apparatus and prolong the last impulse of said series in the event it is desired to transmit a call code to the same station and to sound said audible signal so long as such impulse is prolonged, and by such prolonging of such impulse maintain said cycle marking relays energized, means including said centralized trafiic controlling system and a call coding key to discontinue said prolonged impulse and stop said audible signal and to transmit a calling code to the selected field station, and call code decoding means at such field station responsive only if the transmitted call code corresponds to the code characterized by the call code decoding means at such field station and then only if that perpendicular field station has been selected and still has its cycle marking relays energized.

4. In combination; a central office and a plurality of field stations each having a branch line leading to one or more call stations; a telephone bell for each of said call stations; control apparatus at each of said field stations; a single line circuit connecting said office and each of said field stations; a line relay controlled by current in said line circuit at each of said field stations; code transmitting means including said line circuit and line relays for transmitting a code from said ofiice to any one of said field stations to control apparatus at such station and to connect contacts of the line relay at such station in a circuit for relaying a supplemental code into the branch line extending from that field station; and other code transmitting means at said oillce for transmitting a supplemental code to any one of each of the call stations on the branch line leading from the selected field station, at which said traffic controlling devices were controlled, through the medium. of said line circuit, the line relay at the selected station and. the relaying circuit including contacts of such line relay; and decoding means at each of said call stations for decoding the supplemental code and sounding the callbell for that" call station which has decoding means conforming to the supplemental code transmitted.

5. In combination; a central ofilce and a plurality of field stations each having a branch line leading to one or more telephone stations; a call bell for each of said telephone stations; control apparatus at each of said field stations; a single r line circuit connecting said office and each of said field stations; a line relay controlled by current in said line circuit at each of said field stations; cycle marking relays controlled by said line relays so as to be picked up at the beginning of a' code cycle and so as to remain up so long as said line relays are intermittently or continuously picked up; code transmitting means including said line circuit, cycle marking relays and line relaysfor transmitting a code from said office to any one of said field stations to control. a control device at such station and to connect contacts of the line relay at such station in a circuit for relaying a supplemental call code into' the branch line extending from that field station; and other code, transmitting, means at said ofilce for transmitting a supplemental call code to. each of the call stations on the branch line leading from the selected field station, at which said control devices were controlled, through the medium of saidline circuit, the linerelay at the selected field station and the relaying circuit including contacts of such line relay and frontcontacts of said cycle marking relays; decoding means at each of said telephone stations for decoding the supplemental code and sounding the call bell for that telephone station which has decoding meansconforming to the supplemental call code transmitted; a supplemental connection for each branch circuit for connecting said line circuit to such branch circuit including filtering means which permits the flow of audio' telephone current of voice frequency but does not allow the fiow of current of either the main or said sup- L plernental code, and a telephone receiver and transmitter at eachof said telephone stations for communicating with some one at said office over said supplemental connection.

6'. Apparatus for sounding a call bell comprising, a first line circuit connecting a central oifice and a distant field station, a second line circuit connecting said field station with a call station, a line relay included in-said first line circuit at said field station, a plurality of code responsive callselectors at saidcall station, a station selecting relay at said field station, code transmitting means at said ofiice for transmitting a code cycle consisting ofa first-series of impulses and a second' series of impulses of which the first series characterizes a code by the polarity pattern of its impulses and of which the second series of impulses characterizes a code by the impulse duration pattern of its impulses, means at said field station including said line relay to energize said station selecting relayif the first series of impulses characterizes the code for that field station, and means at said field station including said line relay and said station selecting relay for relaying the second series of impulses into said second line circuit to actuate that one of said code responsive callselectors which responds to the impulse duration code pattern constituting said second series of impulses;

7. In combination, a line circuit connecting a central office and distant station, a polar line relay in said line circuit at said distant station, means at said central office for transmitting a cycle of code impulses over said line circuit consisting of a first series of impulses and a second series of impulses of which the first series characterizes a code by the polarity pattern of the impulses and ofwhich the second series characterizes a code by the impulse duration of the impulses, and decoding means at said distant station responsive only if a cycle of impulses is received of which the polarity code pattern of the first series and the impulse duration pattern of the second series of the transmitted impulses corresponds to the polarity code pattern and impulse durationpattern for that station. 

